<template>
  <div class="todo-footer">
    <label>
      <input type="checkbox" v-model="isSelectAll"/>
    </label>
    <span>
      <span>已完成{{completedSize}}</span> / 全部{{todos.length}}
    </span>
    <button class="btn btn-danger" v-show="completedSize" @click="clearCheckTodos">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: 'Footer',
  props:{
    todos:Array,
    selectAll:Function,
    clearCheckTodos:Function,
  },
  computed:{
    completedSize(){
      return this.todos.reduce((pre,todo)=>pre + (todo.completed? 1 : 0),0);
    },
    // 是否全选
    isSelectAll:{
      get(){
        return this.todos.length === this.completedSize && this.todos.length > 0;
      },
      set(value){
        this.selectAll(value);
      }
    }
  }
}
</script>

<style scoped>
  .todo-footer {
    height: 40px;
    line-height: 40px;
    padding-left: 6px;
    margin-top: 5px;
  }

  .todo-footer label {
    display: inline-block;
    margin-right: 20px;
    cursor: pointer;
  }

  .todo-footer label input {
    position: relative;
    top: -1px;
    vertical-align: middle;
    margin-right: 5px;
  }

  .todo-footer button {
    float: right;
    margin-top: 5px;
  }
</style>
